Blown Head Gasket — Bubbling.
 

Compression test:
- US Passenger side (4,5,6) all show 180 psi.
- US Driver Side (1,2,3) show 60 psi, 60 psi, 100 psi.

The coolant is under pressure because of the air forced into the coolant lines During the test.

So I peeked inside with a borescope. I can see fluid in the cylinders and bubbling at the head gasket inside cylinders 1,2,3.

Should I just go all in on a head gasket replacement or should I be looking for a crack somewhere?

No white or smokey exhaust. Just light coolant smell.

Thanks!

A little background on how we got here.

Car is new to me. 62k mi, 1999 model year.

Looks like someone forgot to install a gasket on the thermostat. I've replaced that and the water pump and didn't realize there was a head gasket leak until I got everything up and running with new coolant. I suspect the car overheated and caused this mess.


I've attached a picture from the borescope results referenced from the last message. The is from the first cylinder. Bubbling is at the seam between valves and cylinder wall.

http://986forum.com/forums/uploads02...1727049800.jpg

While you wait for someone who knows more than me to reply, check out Hoffman Machine's web page. There's some good info about cracked heads and repairs. https://hamheads.com/2017/01/16/986-996-porsche-cylinderhead-cracks-explained/

I'm not saying it's not the head gasket. I just know that cracked heads are a much more common cause in these cars.

Totally agree. Head gaskets usually don't leak on these cars. That said... this one is?!

I've done my homework... and I can convince myself that several scenarios are possible:
1. Did something crack and then loosen things up enough to create a head gasket leak?
2. Could the head gasket leak have reduced pressure and prevented a crack from forming?


Trying to figure out the best path to a solution. May contact Hoffman and see what they say if there is no great suggestions here!

Les Hoffmann is a sure path, he would be able to properly inspect your head (and repair it) if you have a crack.